This application claims the priority of German patent document 195 38 796.1, filed Oct. 18, 1995 and PCT patent document PCT/DE96/01978 filed Oct. 17, 1996, the disclosures of which are expressly incorporated by reference herein.
The present relates to a device for supporting cardiac function having elastic filling chambers which exert mechanical pressure and act selectively on the left ventricle region. The chambers can be filled with a medium and evacuated via connection lines.
When the heart fails to pump, the problem is a muscle weakness of the left cardiac chamber, such that insufficient blood volume can be expelled from the heart into the main aorta, and maintaining circulation is no longer ensured. The causes of this pumping failure of the cardiac muscle are varied. For instance, after heart surgery, viruses, deficient coronary circulation including pump failure can lead to loss of cardiac function.
To support cardiac activity mechanically during or following surgery, a number of devices are known. By way of illustration, German patent document DE-33 07 211 A1 discloses a device that can be implemented for supporting the activity of the myocardium. This device is composed of a rigid-walled container housing surrounding at least partially the ventricular region of the myocardium. Pump chambers, which directly deform the cardiac wall at the corresponding sites, are provided on the interior side of the container housing. However, this known device has the drawback that the pressure propagation on certain ventricle regions continues within the organ to such an extent that cardiac regions on the opposite side corresponding to the pressure exerting centers are pressed against the rigid container wall, thereby possibly causing irreversible damage to the heart or the vessels. Moreover, the rigid container wall lastingly impairs the natural expansion behavior of the heart.
Generic pump systems which are able to support cardiac function and are positioned at the heart with the aid of flexible bands are also known. A device of this type is disclosed, for example, in U.S. Pat. No. 5,131,905. However, devices of this type have the disadvantage that the limited width of the attachment bands permits only insufficient fixation effects. Moreover, the edges of the bands rub on the surface of the heart and can lead to irreversible local damage to tissue. Furthermore, attachment of the bands about the beating heart for surgery is very difficult and complicated.
In order to avoid the aforementioned disadvantages, International patent document WO 94/27552 describes a device for supporting cardiac function. The device is provided with two approximately opposite filling chambers that are connected via a U-shaped, rigid rod between which the left ventricle region of the heart is located. A special advantage of this device is that upon compression of the left ventricle region by corresponding filling of the filling chambers, the other cardiac regions can expand without hindrance. Corresponding damage to the surface of the heart due to bruising occurring by way of illustration when hard shells are employed is prevented in this manner.
However, the above described device for supporting cardiac function has the disadvantage that some mobility remains between the filling chambers and the surface of the heart so that slipping of the device on the heart surface cannot be ruled out.